Catherine became suspicious when she began noticing that her husband was putting in more and more overtime; his paycheck just wasn't showing the results.

When she found a credit card receipt showing a room charge at a Lake Elsinore motel, she confronted him.

At first her husband denied having been there, said Catherine, who asked that her last name not be published.

After a lengthy grilling he admitted that he had taken a prostitute to the room but assured his wife that they had not had sex, the Murrieta woman said. That's when she insisted he take a lie detector test -- a polygraph. In so doing, she became one of a growing number of people turning to this tool, once more closely associated with espionage and criminal investigations than with settling personal questions.

According to Jamie Skeeters, president of the California Association of Polygraph Examiners, recent movies like "Meet the Parents" and reality TV shows like "Meet my Folks" -- both of which include polygraph tests in their plot lines -- have contributed to the increase in the use of polygraphs as infidelity detectors.

Catherine set up her husband's session with a certified polygraph examiner, and when he flunked the test, he finally confessed to his philandering ways, she said. The Murrieta couple is now seeing a counselor and trying to save their 10-year marriage, she added. She said she doesn't regret her decision to have him tested.

"That was the best $200 I spent in my life," Catherine said.

Temecula private investigator Mike Roberts, who handles many domestic cases, says that more and more husbands and wives are asking their spouses to take polygraph tests, which he sets up for them with a certified polygraph examiner. He said he estimates that about 60 percent of the tests he has done are on husbands.

At times, the accused spouse will try to bluff his or her way out of the situation by offering to take a polygraph. he added.

When their bluffs are called and the test shows they have not been telling the truth, many still insist on their innocence, he said. That's why polygraphs are only one facet of the investigative process, he added.

"The most common tools are still pictures or videos, because a picture is still worth a thousand words," Roberts said.

How it works

Polygraphs -- which some research shows have a reliability rate of more than 90 percent -- are based on the fight or flight principle, said Skeeters, the polygraph association president. Fear triggers changes in certain physiological functions when a person is confronted with a question about something they are trying to hide, he said. Other research puts the percentage lower, however, and polygraph tests still are rarely admissible in court.

The test measures breathing, heart-rate response and electrical charges emitted by the body, known as "galvanic skin response." When people are being deceptive, their breathing gets shallower, their heart rate and blood pressure increase and their bodies emit more electrical discharges.

Some people try to beat the test by controlling those involuntary responses, several examiners said. But certified examiners receive training in countermeasures and can usually weed out those trying to cheat, said San Bernardino-based examiner Chris Gibson.

"Controlling the breathing is the most obvious (method)," he said, recalling a man who was only taking a breath every 25 to 30 seconds during his exam.

"He said he was a runner, but at the end of the test his breathing (went) back to normal," Gibson said.

Some people will put a thumbtack in a shoe, puncturing themselves on some innocuous questions in hopes of skewing the test results by increasing their heart rate through pain, he said.

Skeeters said he's seen it all when it comes to trying to use pain to cheat the test.

"I've had people use plastic-comb teeth in their gums or needles between their teeth to bite down on and bite their tongues," he said.

And while examiners are trained to ask the right questions, sometimes the clients can skew the results.

Skeeters recalled one powerful, wealthy man who came to see him because he was certain his wife was having sex with the family gardener. Although he advised the man to be more general in the questions, the husband insisted that Skeeters specifically ask the wife whether she had committed adultery with their gardener. The wife passed the test, Skeeters said, and the couple left.

A few weeks later, however, the husband returned and asked him to retest the wife -- this time asking her if she had committed adultery with any other man. When the wife came into Skeeters' office, she told him, "I think we have a problem," Skeeters said. "I won't pass the test, because I'm having sex with the pool guy, not the gardener."

He added that of the tests that he has administered on husbands and wives, about 50 percent show deception.

Shoot the messenger

Skeeters, who conducts tests across Southern California, said he too is seeing a growing use of polygraphs as a tool to nail cheating spouses, a trend he attributes, in part, to the increasing exposure of polygraphs in movies and television.

But not all examiners like the new trend. Unhappy with what the test results reveal, many wives and husbands will blame the examiner, according to Brian English, a certified polygraph examiner with San Diego's Backster Associates Inc.

For that reason, many examiners -- including him -- do not handle domestic cases, he added.

"We stopped doing them about two years ago," English said.

Instead of a polygraph, he recommends that couples seek therapy to deal with the real issue, he said -- trust.

Domestic polygraphs are just not worth the emotional toll, San Bernardino-based polygraph examiner Michael Lynch said.

"No matter how the test turns out, the examiner is often the bad guy," he said.

Not only that, but the examiner often has to deal with couples' reactions to the tests, he added.

"I have had husbands and wives actually break into fisticuffs over the results, whether they lied or not," he said.

Lie detection nothing new

While polygraphs have been used and refined since the first half of the 20th century, other forms of lie detectors have been around for centuries.

The Chinese had a special technique for catching liars some 10 centuries before Christ: The accused chewed a mouthful of rice; if it was dry when he spit it out, he was deemed guilty.

In ancient India, priests put lampblack on a donkey's tail in a darkened room. They then told a group of suspects to go into the room and pull the donkey's tail, warning them that the "magic" donkey would cry out when the culprit touched the animal. The person who exited the room without lampblack on his hands was presumed guilty.

For those who can't afford the estimated $350 to $700 cost that most examiners today charge for domestic polygraph exams, there are other solutions.

Voice-stress analysis devices can be bought for about $300, local investigator Roberts said, although their reliability is significantly less than polygraphs.

And for those who are really on a tight budget, a Chicago company markets a device -- "The world's first hand-held lie detector" -- over the Internet for $24.95. A spokesman for 911 Technology said last week the company has sold more than 5,000 "Handy Trusters" in the past year, although he said he couldn't identify any scientific research that has been conducted to verify the company's claim of an "84 percent accuracy rate."

As Catherine and her husband continue their marriage counseling, two years after his infidelity, she said she is still uncertain whether the marriage will last. But if the outcome is divorce and she eventually remarries, one thing is certain, she said -- her fiance will have to take a lie-detector test to answer questions about his past before she will say "I do."

"People should know," Catherine said.

Contact staff writer William Finn Bennett at (909) 676-4315, Ext. 2624, or wbennett@californian.com.